Answer:
In Bible times, the dusty and dirty conditions of the region and the wearing of sandals necessitated foot-washing. Although the disciples most likely would have been happy to wash Jesus' feet, they could not conceive of washing each other's feet. This was because in the society of the time, foot-washing was reserved for the lowliest of menial servants. Peers did not wash one another's feet, except very rarely and as a mark of great love. Luke points out (22:24) that the disciples were arguing about who was the greatest among them, an attitude that precludes a willingness to stoop to wash feet. When Jesus moved to wash their feet (see also John 13:1-16), they were shocked. His actions serve also as symbolic of spiritual cleansing (vs. 6-9) and a model of Christian humility (vs. 12-17). By washing His disciples’ feet, Jesus taught the lesson of selfless service that was supremely exemplified by His death on the cross.

The foot-washing was an example, a pattern. Many groups throughout church history have practiced literal foot-washing as a church ordinance. However, present culture in many lands does not call for washing dust from the feet of one's guests. Although the Lord's Supper was practiced, the early church apparently did not practice foot-washing as an ordinance in church gatherings.

This passage emphasizes inner humility, not a physical rite. A Christian widow's practice of "washing the feet of the saints" (1 Timothy 5:10) speaks not of her involvement in a church ordinance but of her humble, slave-like service to other believers. To refuse to follow the example of Jesus is to exalt oneself above Him and to live in pride. “No servant is greater than his master” (John 12:26).